laying slabs

I'm landscaping my brothers garden at the moment.

I am laying slabs on a slight slope with decorative aggregate around the slabs.

There will be a space between the slabs.

What should I use to lay them on the soil. Can I get away with using slab fix. If not should I use a mortar mix. If so what type of mortar mix should I use.

Any advice Guys.

Personally I'd never lay slabs on top of soil... this is a recipe for future problems due to ground heave etc.

Digging out, 75mm of MOT/DtP1 fully compacted (if foot traffic only) as the sub-base with a solid mortar bed for the slabs should be what you are looking at for any patio area. Or are you just laying stepping stones?

shenks said:

Personally I'd never lay slabs on top of soil... this is a recipe for future problems due to ground heave etc.

Digging out, 75mm of MOT/DtP1 fully compacted (if foot traffic only) as the sub-base with a solid mortar bed for the slabs should be what you are looking at for any patio area. Or are you just laying stepping stones?

Click to expand...

Thanks for the reply Shenks.

You are probably right in saying that they are stepping stones. They are 450mm by 450mm. Are these laid differently from what you have already mentioned.

Excue my ignoance but what is MOT/DtP1

Cheers John

If you are laying stepping stones then I'd suggest that you use MOT/DtP (otherwise known as crusher run which is a combination of various sizes of gravel from about 40mm down to dust) to create a 'bed' or 'sub-base' of approx 75 mm thick below where each stepping stone is going. You should also extend this past the perimeter of each slab, so if each slab is 450mmx450mm then I'd have the sub-base approx 50mm past each edge. This will eventually be covered by your dressing layer of gravel.

Also since this is for stepping stones, you could actually do a run along the path that the stepping stones are going to take using the crusher run and then space the slabs out accordingly. Once you have compacted the crusher run (best performed using a whacker plate but you could do it by hand, just ensure that it is quite solid once you have finished), then lay a solid bed of mortar (6:1 mix of sand/cement) where each slab is going to go. Use a rubber mallet or similar and a spirit level to ensure that the slabs are level.

Remove any excess mortar that spills, but haunch the edges slightly so that the bed is similar to this shape /#####\

You can then infill the spaces between the stepping stones with the gravel as necessary. I usually have the gravel level set below the top face of the slabs so that it doesn't migrate on to the tops of them too easily - about 15mm below.

Hope this explains it for you...

Excellent information Shenks.

Thanks

is MOT/dpt1 same as using ballast?

No ballast is clean (sorted) gravel of varying sizes then mixed with sand.

MOT is straight from the quarry crusher bin with various sizes but more importantly fines and dust which is much finer than sand and will compact properly.

The Weegie said:

shenks said:

Personally I'd never lay slabs on top of soil... this is a recipe for future problems due to ground heave etc.

Digging out, 75mm of MOT/DtP1 fully compacted (if foot traffic only) as the sub-base with a solid mortar bed for the slabs should be what you are looking at for any patio area. Or are you just laying stepping stones?

Click to expand...

Thanks for the reply Shenks.

You are probably right in saying that they are stepping stones. They are 450mm by 450mm. Are these laid differently from what you have already mentioned.

Excue my ignoance but what is MOT/DtP1

Cheers John

Click to expand...

"Stepping stones" are slabs placed some distance apart say, across a lawn. Laid in a similar way to paving but not quite the same. Patios need a full MoT bed and a full mortar bed, not discrete spots. I took it to mean you were paving an area, with gravel in the cracks between them. Was I wrong?